Aseptic necrosis has been identified in two men who have worked in compressed air using the currently approved OSHA decompression schedules in excess of 36 psig. 39 men can be identified in Milwaukee as having been exposed to the OSHA schedules since their inception in 1970 but who have not been followed-up radiographically. The purpose of this research is to trace these men, to perform radiologic surveys on them and to determine whether or not they have contracted aseptic necrosis. It is proposed that these men be x-rayed as soon as they can be located, six months later and then finally, one year after the first x-ray. It is also proposed that Technetium 99m bone scans be carried out on these men at the beginning and at the end of the year to determine normal or pathologic activity in the regions of their humeral and femoral heads. The survey should be completed within 14 to 18 months of its beginning and when the x-rays are correlated with the work history of the individuals involved, it should be possible to state at what maximum pressure the current OSHA tables for decompression of workers in civil engineering begin to fail.